Electronic circuits in general are typically designed to operate in a particular operating range. For example, a switch-mode power supply (SMPS) may be designed to receive 12 V and generate an output voltage of 3.3 V capable of supplying 1 A to a load.
Some systems may have power-up requirements for proper operation. For example, a processor may have multiple supply inputs, and the processor may be designed to have a particular supply input having a voltage that is always higher than another supply input for proper operation. Similarly, an electronic device may be designed to have a supply input increase its voltage at a particular rate during a power-up event for proper operation.
Exceeding some of the specifications of an electronic device may cause temporal malfunction or permanent damage to the electronic device or other devices coupled to the electronic device. For example, shorting an output of an SMPS to ground may cause an overcurrent event that cause permanent damage to the SMPS (e.g., to one or more power FETs), and, in some case, even to the PCB and PCB traces. As another example, in some cases, abruptly turning on a power supply may cause an in-rush current that may cause temporal or permanent damage to the power supply and/or to components coupled to the power supply.
Fuses have been used to protect electronic devices, such as power sources, loads, cables, wiring systems, electrical equipment, and other electrical components from an over-current event. A fuse is typically a low resistance element that would interrupt the flow of current through it when current beyond the fuse's current rating flows through it.
An electronic fuse (e-fuse) is an active circuit that provides over-current protection.